Shi-Biao Zheng

Teleportation of atomic states via resonant atom–field interaction

Abstract A scheme is proposed for the teleportation of an unknown atomic state. It is based on resonant atom–field interactions.

A simplified scheme for testing complementarity and realizing quantum eraser

We propose a simple method to test Bohr complementarity in the context of cavity QED. When an atom is sent through two resonant classical fields, the probability of finding the atom in definite states exhibit interference fringes. Replacing the first classical field with a quantized cavity field, the interference is destroyed since the which-path information for the atom reaching a definite state is recorded in the cavity. The associated quantum eraser can also be realized.

Simplified realization of multi-atom Greenberger–Horne–Zeilinger states with dispersive cavity QED

Abstract We propose a simple scheme for the generation of multi-atom Greenberger–Horne–Zeilinger (GHZ) states. Three appropriately prepared atoms are sent through a nonresonant cavity filled with a coherent field. The whole system evolves into an entangled state, in which two three-atom maximally entangled states are correlated with coherent field states separated by π in phase space. The field is then driven by a classical current and measured by an atom, which collapses the atomic system onto a GHZ state. The scheme can be easily generalized to prepare n -atom maximally entangled states.

Simplified quantum logic gates with trapped ions in thermal motion

Abstract A simplified scheme is presented for realizing a two-bit quantum logic gate in an ion trap. As the scheme of Sorensen and Molmer [Phys. Rev. Lett. 82 (1999) 1971], our scheme is insensitive to the interaction with the environment. However, the quantum controlled-not gate between two ions can

Preparation of superpositions of Fock states via the interaction of a multi-level atom with the field

A simple scheme for generating superpositions of Fock states of a quantized electromagnetic field is presented. It is based on the detection of a suitably prepared multi-level atom in its lowest level after its interaction with the cavity field.

Synthesis of the quantum states of the motion of a trapped ion

We propose a scheme for generating superpositions of several coherent states of the motion of a trapped ion. In the scheme, an ion is trapped in a two-dimensional anisotropic harmonic potential and driven by several travelling-wave laser fields tuned to the ion transition. After a short interaction time, a conditional measurement of the electronic state may leave the vibrational motion in the X axis in a superposition of several coherent states along a straight line.

A proposal for testing symmetrization postulate for photons via Raman atom-field interaction

Abstract A proposal is made for testing symmetrization postulate (SP) for photons in the context of cavity QED. In the scheme sequences of two Λ-type three-level atoms are sent through a cavity filled with a coherent field. After Raman-type interactions, the atoms are state-selective measured. The two atoms would be detected in the same state when the SP holds. The probability that the two atoms are found in different states characterizes the violation of the SP.

Proposal for direct measurement of the Wigner function of a weak cavity field around the origin using resonant atoms

We propose a scheme for the direct measurement of the Wigner function of a cavity field with no more than three photons around the origin. In the scheme the cavity field is first displaced by a small amount. Then a two-level atom is sent through the cavity. After a resonant interaction time the difference between the probabilities of the atom being in the ground and excited states is directly related to the Wigner function for the field state. The scheme can also be used for conditional generation of four-photon and six-photon states using two and three resonant atoms, respectively.

A simplified method to test the symmetrization postulate for photons

A scheme is proposed for testing the symmetrization postulate (SP) for photons in a cavity. In the scheme a two-level atom interacts dispersively with a cavity field initially in a q-deformed coherent state, and is manipulated by two classical fields. The probability that the atom does not flip from one state to the other characterizes the violation of the SP.

Quantum nondemolition measurement of atomic inversion and generation of nonclassical atomic states

We propose a quantum nondemolition (QND) measurement of the atomic inversion number of collective atoms confined in a cavity in the context of cavity QED. After a perfect QND measurement the atomic system reduces to a Dick state. We also show how we can generate various nonclassical atomic states.